text: import unittest2
  from zounds.core import ArrayWithUnits
  from zounds.timeseries import TimeDimension, Seconds, VariableRateTimeSeries
  from .onset import BasePeakPicker
  import numpy as np
  
  
  class BasePeakPickerTests(unittest2.TestCase):
  
      class PeakPicker(BasePeakPicker):
          def _onset_indices(self, data):
              indices = np.random.permutation(np.arange(len(data)))[:3]
              indices.sort()
              return indices
  
      def test_peak_picker_returns_variable_rate_time_series(self):
          data = ArrayWithUnits(
              np.zeros(100),
              dimensions=[TimeDimension(frequency=Seconds(1))])
          picker = BasePeakPickerTests.PeakPicker()
          results = next(picker._process(data))
          self.assertEqual(3, len(results))
          self.assertIsInstance(results, VariableRateTimeSeries)
  